Machine for testing electromagnetic sound reproducers



Nov. 8, 1927.

` R. H. STACY MACHINE FOR TESTING ELECTROMAGNETIC soUND REPRoDucERsFiled March ,18. 1927 INVENTOR. 53a ///Szc Y gf TTORNEY Patented Nov, 8,192?.

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Stets? mme RAY n. s'rAoY, or EAST enanenitaw Jnnsn, Assrcnoaro Bananasnascita-Y" TORES INC., QFXTEVARK, NEVI' JERSEY; AA ooneoiaa'rro'n orYAiiiiav JERSEY.

MACHINE Fon rnsrntannncrnoivreenn'rio sounn nnrncnuonnsl applicationflied March 1s, 1927. `seriai No. 176,437.

ers and more particularly to a depth grind ing testing machine tor thejpole pieces ot sound reproducers.

One ot' the objects of my invention is to` provide a machine for testingthe grinding depth ot' the. pole pieces of electromagnetic *soundVreproducers for y insuring a `magnetic.

gap of a predetermined dimension between the Varmature member andthe.pole pieces ot an electromagnetic soundreproducer.

Another object ot my vinvention is tojprovide a direct reading depthtesting'machine tor test-ing electromagnetic sound re roduc-l t e.

ers during the course of manufacture of` vthe soundreproducer'tor.insuring an accu- Fig. 1 von line 2-2 thereof ;n and Fig.3 is a lateral cross-sectional .view taken through the machine on line3-3 of'Fig. 1.

Heretotore in tlievmanu'tacture of electromagnetic sound reproducerson'f'a quantity production basis it has been ditlicult terapidly testelectromagnetic sound reproducers passing through a production program:tor determination or' the grinding depth of the pole pieces. By reasonot' the ditliculty in securing a rapid and accurate knowledge ot thedepth of the pole pieces, the normal dimension of the magnetic gapbetween the driving armature and the pole pieces of the electromagneticdriving system has been generally neglected, and

sound reproducer derived vunder Yconditions of extensive productionhave'not been uniform. The machine ot my invention was developed with aview oin rapidly determin-V ing the grinding depth of the pole pieces ofan electromagnetic sound reproducer in such invention relates broadlyVto machines e tor testing electroniagneticA sound reproduc- 2 is alongitudinal cross-sec. vtional view taken throughthe machine of as aresult the operf l ating characteristics of the electromagnetic vices'18 and 2O separatelyI manner that relatively unskilled labor mightaccept or reject electromagnetic sound reproducers passing through aproduction program so that Vthe rejected electromagnetic i soundreproducers of too small or too large a magnetic gap might be returnedfory re-` grinding or replacement ot the'pole pieces, while Vtheacceptedy electromagnetic sound ieproducers might be passed rapidly'tothe next productiony process in the manufactur- -program.p, 1 fReferring to the drawings in more -detaih reference 'character 1represents a base on which the testing apparatus ,is mounted, ,the hasebeing ,spaced from a supporting surface by means ot' clip 4members' 2. Ade-V pending casing 3 surrounds the peripheral edge of the base 1providing a casing for the operating mechanismbeneath the base. A bottomcover the mechanism beneath tlre base. Sets ot aligned slots areprovided `onoppo'site sides of thercenter ot base,1, and through theseslots sets ,ot adjusting screws=7 and 8 are passedv and 'entertherectangular bars '9 and 10. By loosening thescrews 7 land 8 `therectangular bars may belaterallyl adjusted with respecttoeach other andbrought relatively close together or moved relatively tari apart.Therectangular bars provide 'a support for the casing` ot theelectromagnetic sound reproducer indicated at 11.` The electromagneticsound reproducer is illustrated in Fig. 3V in `position upon the testingniachine where pole pieces 12 have the tips 14 and -15 thereof presentedtor' test with re` spect to vgrinding depth. `The .tips A1/1.-` and' 15of the-pole pieces may contact with plungerl during the process ofdetermin-y ing the grinding depth of the polel pieces. The plunger 16maybe adjusted by means oit screw device 18 in the pivotally mountedlever 17 which is journaled in members 19 suspended from. theunder-surface of base 1.l At the-opposite end of the leveri17 anadjustable member control of ascrew device 20, the adjustable" member 22havingY a head l3() thereon aiv ranged'to abut with the plunger member24 ot Vthe micrometer 23, which is supported from a bracket 25 onbase 1. rlhe screwV de- I control the posi tion of plunger 16 and member22. Each screw device is in the form ot a knurled flange having a. screwthreaded shank which 4 completes the enclosure ot 10o' 22 is positionedunder may be rotated to a desiredposition and then*v gllpped in aselected position by means. of

nuts engaging opposite sides of the lever 17.

'The lever 17 is normally balanced against .Y spring members 21 and 28for Y of the indica-tor 27 on the scale Zero reading 26, but uponpassing a pole tip, such as pole tip 15 in engagementwith the plunger16,- a reading on scale 26 is obtained showing the grinding depth of thepole tip. Oversize pole tips can be readily detected by the 'abutmentof` the rpole tip withY the lplunger 16 andwhile ob'- serving. thereading of indicator with respect to scale 26.l By regrinding the polel, tips and again testing the Agrinding depth the required normalreading may be finally' obtained and the electromagnetic soundreproducer passed for'tlie next step in the pro-Y duction` program, j

The machine may be readily adapted for rvarious sizes of electromagneticsound reproducers and a normal setting` for the remeans of screw devices18 and 20.

quired grinding depthreadily adjustedr by The machine ofmy invention hasproven very effective in quantity production of electromagnetic soundreproducers and insures the more uniform operationof thev soundreproducers which pass through'V the production program and arepresented for inspection prior to acceptance and-shipment.

While VI have described the testing machine in one of its preferredconstructions, I desire that it be understood that modifications indetail may be made and thatv no limitations upon my invention areintended other than are imposed by the scopel of the appended claims.

. What I claim as new andj desire to secure by Letters Patent oftheUnited` States isas follows:

1. A machine for testing the v,f frindin'g depth of electromagneticsound reproducers comprising a supporting base, means for rel ceivinganv electromagnetic sound repro'duccr in spaced relation to 'said base,with'thepole tips thereof depending toward said base, a pivoted levercarried on said base, a micrometerpmounted adjacent one end of lever formeasuring the displacement of said lever, and means mounted upon theother end of said lever for engaging the pole tips` of saidelectromagnetic sound reproducer for effecting a displacement of saidlever for measuring the grinding depth of said pole tips on saidmicrometer.'

2.' yA. machine for testing thegrinding depth of the pole tips of anelectromagnetic Y sound reproducer comprising a base,A niember, a pairof adjustable bars for'receiving the electromagnetic sound reproducerwith the poletips thereof depending downwardly toward said; base member,a lever pivotally mounted upon the under-surface of said base, anadjustable-member carriedxby each end of said lever, a micrometerpositioned upon oneR end of said base for enga-gement K withtheadjustable member on one end of said lever, theA adjustable member onthe opposite end' of said leverbeing arranged pivotally mounted beneathsaid base member, a screw device adjustably positioned in each end ofsaid lever and extending up-V wardly through said base, a micrometerycarried by said base and controlled byl the screw 'device in onev endAof said lever, the electromagnetic device on'test being positioned onsaid supporting bars with the pole tips thereof arranged to engage thescrew device in the opposite end of said lever for effecting adisplacement of said lever and indicating the grinding depth of saidpole tips by readings of said micrometer.

Intestiinonyxwhereof IlaftX my signature` l -RAY H. STACY.

